Noobie building garage - Several questions

[VT-Rider]

Hi, Noobie Lurker here. Hi!

I’m building a heated 30x30 detached garage/shop at 2250’ in central Vermont. 6” 4000 psi concrete floor for possible 4-post (Advantage) moveable lift, with 8” stub wall. 2x6x12 side walls, WF18 steel center beam, 12x2x15 first floor ceiling beams, 12/12 pitch gable roof with 12x2 roof rafters. Two 10x10 insulated doors w/jack shaft openers. Hardi plank siding. Screwed on black metal roof. 19/34 insulation. Several questions:

1. Heat with a Modine Hot Dawg HDS45 (outside combustion air) 45,000 BTU. I’d normally keep space at ~50F (65F when working there) and Modine recommends SS heat exchanger due to more condensation. I’d also like dual range burner, 50% for normal operation, 100% when doors open. However, Modine does not offer that 45KBTU (SS / variable) configuration. What’s more important, SS burner or dual range?

2. As I want to heat 2nd floor, do I need knee walls and a ceiling, or just run roof rafters up to the 15’ (12/12) high point?

3. ZIP sheathing or plywood and Tyvec? Builder says when he tapes Zip as he goes, doesn’t have a Zip roller. I’m leaning toward ply/Tyvec.

4. Closed cell (purple) closed cell foam or rock wool insulation? Even if foam is exothermic, is there a min recommended application temp? It’s getting cold here. Do I need to ventilate the roof (as with rock wool), or just spray insulation on the underside of the Zip/plywood roof?

Probably a lot more... Thanks

 

[glentre]

Six inch concrete is an overkill if you're only doing it because of the four post lift you plan to install. Four inch with mesh is fine.
Glen

 

[CraigStu]

My SIL just used the zip system roofing plywood and tape. He is very happy w/ how it went on and how well the tape works.

 

[WisJim]

I'm at the point of getting insulation estimates for my shop and garage building, and the spray foam contractors are telling me they can properly apply foam down to 20 degrees, or even colder outside if they heat the building some to get the sheathing temperature up. I have waferboard sheathing with steel siding and roofing. The contractors differ in their opinions as to ventilation space between the foam and the roof sheathing, and my research on this email leaves me undecided (maybe confused).

 

[spudley]

1. Heat with a Modine Hot Dawg HDS45 (outside combustion air) 45,000 BTU. I’d normally keep space at ~50F (65F when working there) and Modine recommends SS heat exchanger due to more condensation. I’d also like dual range burner, 50% for normal operation, 100% when doors open. However, Modine does not offer that 45KBTU (SS / variable) configuration. What’s more important, SS burner or dual range?

If you're leaving heat on all winter, you shouldn't have condensation on the heat exchanger. But I'm wondering how often you'll be leaving a door open so I'd go with the SS heat exchanger.

2. As I want to heat 2nd floor, do I need knee walls and a ceiling, or just run roof rafters up to the 15’ (12/12) high point?

Are you required by code to meet any insulation standards? A 2x12 has plenty of room for insulation using closed cell foam (expensive). A ceiling would limit wasted heat space and provide an opportunity for cheaper blown in insulation. Doubtful you'd be using areas where rafters meet top plates so knee walls would also limit heating use, and allow less expensive insulation.

3. ZIP sheathing or plywood and Tyvec? Builder says when he tapes Zip as he goes, doesn’t have a Zip roller. I’m leaning toward ply/Tyvec.

On my garage, I used Tyvek over OSB on the walls, synthetic under shingles. I'd use Zip if on a house.

 

[matt_i]

The 45k seems low to me. I have done no calculations either. I'm thinking 60-80 is going to be needed so its not running all of the time.

Along those lines its going to be tough to prevent stratification with the 2nd floor being at a completely different temp than the bottom, and struggling to keep it warm in the bottom. So to take that idea further, I'd look at two different units, maybe a 45k upstairs and a 45k downstairs with some kind of door in-between to keep the spaces separated. Ceiling fans will help but I can feel the stratification even in my 11ft shop.

 

[NUTTSGT]

Tell your contractor to get a Zip roller, like $35, and do it correctly. It has to be rolled for warranty claims.


I'm doing an addition on my garage right now. I used Zip because it was $2/ sheet more. I just came in from doing some taping and rolling. It's easy and would go faster with another person. .. its also cold and not wearing gloves. It kept sticking to my gloves and hard to peel with them on.

 

[VT-Rider]

65F here today. Slab got poured, 6” curb wall in next week - to keep the sheet rock dry. Going with Zip, 19/34 rock wool, vapor barrier, sheet rock. 30” fire exit outward opening door (no outside hardware) on back wall. 4’ knee walls and 9’ ceiling upstairs. Contemplating a loft door on front side for the rare case of something large not making it up the 36” corner staircase.

I’m in a “Forest Reserve District” up on a mountain (for VT anyway) and Devine Review Board doesn’t want to see the building from down in the Valley. Metal roof is to be black. I’m working out colors for a “stealth” building...